Semiconductor chips, so-called VCOs (voltage controlled oscillators) can be used to generate these extremely high frequencies. Suitable antenna structures for matching electrical conductors to free space are required for transmission, reception, and transfer. Further, semiconductor chips with DSP (digital signal processor) circuits can be used to process microwave signals. In this case, with increasing frequencies, the antenna dimensions approach the dimensions of the semiconductor chip.
FIGS. 15 to 18 show antenna structures of the prior art which are designated as “strip”, “slot” and/or “patch” antennas. In this case, the expression “strip” relates to the strip shape of the connecting lead to a radiation plate, the designation “slot” relates to the mode of coupling-in the microwave energy via an aperture in the direction of the radiation plate, and the designation “patch” relates to the radiation plate itself.
FIG. 15 shows a schematic perspective view of a patch antenna 20 with a strip antenna structure which has a stripline 29 as the connecting lead to a radiation plate 21. The radiation plate 21 allows the electromagnetic microwaves to be coupled to free space. For this purpose, the “patch antenna structure” in FIG. 15 is disposed on an insulation layer 16 of dielectric material whose relative dielectric constant ∈r typically lies between 1≦∈r≦3.5. Supply and transmission leads can be disposed in interposed structured metal layers 14 and 15 while a lower metal layer 54 closed in the area of the patch antenna forms a groundplane to the antenna at ground potential to achieve directionality of the radiation plate 21.
FIG. 16 shows a schematic exploded perspective view of a patch antenna 20 with a slotted antenna structure 23. This variant also has a stripline 29 as a connecting lead to the antenna structure 34. However, the stripline 29 is not directly in ohmic contact with the radiation plate 21, as in FIG. 15. Rather, the energy transmission takes place via a microwave insulation region 18 which is dimensioned as an antenna coupling region 24 and forms a resonator cavity 25. This resonator cavity 25 is formed by an insulation layer 16 with a relative dielectric constant 1≦∈r≦3.5.
A slotted electrode 28 has an aperture 26 with coupling slot 27 where the slot-shaped aperture 26 is superposed with the spaced stripline 29 so that they intersect and form a coupling-in point for the antenna coupling region 24. A lower metal plate 54 closed in the area of the antenna structure terminates the antenna structure 34 to form a groundplane and improve the directionality of the antenna structure. A monopolarized and aperture-coupled microwave antenna can be implemented by this structure.
FIG. 17 shows a schematic, exploded perspective view of a patch antenna 20 with a double-slotted antenna structure. This variant has two striplines 29 and 32 arranged at right angles to one another, which cooperate with two coupling slots 26 and 31 of a double-slot electrode 30 arranged at right angles to one another. The antenna structure has two resonator cavities in corresponding microwave insulation regions comprising insulation layers 16 and is also designated as a dual-polarized and aperture-coupled patch antenna.
In order to come close to a relative dielectric constant ∈r=1 in the antenna coupling region, the insulation layers 16 shown in FIG. 16 and/or FIG. 17 are replaced by spacers which hold the structured metal layers apart. For this purpose, however it is necessary for the metal layers to be impact-resistant and self-supporting or reinforced by corresponding insulation panels. This type of structure is mechanically sensitive and as the slotted electrodes 28 become smaller and the radiation plates 21 become smaller, this can no longer be implemented in practice for frequency ranges over 50 GHz. There is accordingly a need to provide a more reliable antenna structure for extremely high frequencies.
A further disadvantage of conventional microwave techniques is the plurality of different components which need to be interconnected on a superordinate circuit board so that parasitic structures disadvantageously impair the reliability and function of the circuits.
FIG. 18 shows a semiconductor module 60 according to the prior art of DE 103 36 171 B3. This semiconductor module 60 has components 6 for microwave engineering, where semiconductor chips 12 and 22 with flip-chip contacts 62 are arranged in a cavity 61 of a multilayer carrier substrate 58. A plurality of vertical conductor tracks 59 lead through insulation layers 16 of the carrier substrate 58 in the edge zones 37. On a freely accessible upper side, the multilayer carrier substrate 58 has a radiation plate 21 of a patch antenna 20 which is ohmically contacted by a vertical connecting lead 55, similar to a stripline, where the vertical conductor track 55 fulfils the function of a conductor track connecting lead. The multilayer carrier substrate 58 is connected to external contacts 40 of the semiconductor module 60 by means of an anisotropically conducting filling material 56 and by means of vertical conductor tracks 64 through a main board 57.
This type of semiconductor module 60 has the disadvantage that it is based on vertical conductor tracks 59 which must be passed through a plurality of insulation layers 16, which causes a considerable financial expenditure. The application of a cavity 61 and the loading of the cavity with the semiconductor chips 12 and 22 is also a cost-intensive solution, especially as surface-mountable flip-chip contacts are to be fixed. Furthermore, the installation of a vertical connecting lead 55 to the radiation plate 21 of the patch antenna 20 for ohmic contacting of the radiation plate 21 requires a complex structuring process of a plurality of insulation layers with metal contact vias.
The known semiconductor module has the disadvantage that reflections occur over the vertical conductor tracks and interference signals can be coupled-in, especially as these vertical conductor tracks act like vertical antenna rods which can receive interference signals.